Major depression represents one of the most common mental illness, affecting between 5-10% of the population. The disease is characterized by extreme changes in mood which may also be associated with psychoses. It has generally been found that most antidepressant agents exert significant effects on the regulation of monoamine neurotransmitters, including serotonin.
A number of types of antidepressants have been developed in recent years. Many of these compounds regulate serotonin (5-hydroxytryptamine; 5-HT). Trazodone controls the actions of 5-HT while fluoxetine is a potent and selective inhibitor of 5-HT reuptake. 3-Chloroimipramine which inhibits both 5-HT and norepinephrine reuptake has been extensively used as an antidepressant in Europe and Canada. Other compounds which are of current interest or have been examined as antidepressants include fluvoxamine, citalopram, zimeldine, sertraline, bupropion and nomifensine. Fluvoxamine facilitates serotoninergic neurotransmission via potent and selective inhibition of serotonin reuptake into presynaptic neurons.
The serotonergic neural system of the brain have been shown to influence a variety of physiologic functions, and the compounds of the present invention are predicted to have the ability to treat in mammals, including humans, a variety of disorders associated with this neural system, such as eating disorders, depression, obsessive compulsive disorders, panic disorders, alcoholism, pain, memory deficits and anxiety. Other indications for antidepressants, such as fluvoxamine, include unipolar depression, dysthymia, bipolar depression, treatment-resistant depression, depression in the medically ill, panic disorder, obsessive-compulsive disorder, eating disorders, social phobia, and premenstrual dysphoric disorder.
The adverse effects occurring most frequently during treatment with selective serotonin reuptake inhibitors (SSRI(s)) such as fluvoxamine are gastrointestinal disturbances, such as, for example nausea, diarrhoea/loose stools, constipation, with an incidence of 6 to 37% (Drugs 43 (Suppl. 2), 1992). Nausea is the main adverse effect in terms of incidence. These adverse effects, although mild to moderate in severity, shy some patients away from treatment with SSRIs. The percentage of patients withdrawing because of nausea ranges from 3 to 8% of the patients. Moreover it has been frequently observed that after administration of SSRIs, patients suffer from dyspepsia. Fluvoxamine also causes a variety of other adverse effects including anorexia, dry mouth, headache, nervousness, skin rash, sleep problems, somnolence, liver toxicity, mania, increased urination, seizures, sweating increase, tremors, and Tourette's syndrome.
Drug toxicity which causes adverse effects is an important consideration in the treatment of individuals. Toxic side effects resulting from the administration of drugs include a variety of conditions which range from low grade fever to death. Drug therapy is justified only when the benefits of the treatment protocol outweigh the potential risks associated with the treatment. The factors balanced by the practitioner include the qualitative and quantitative impact of the drug to be used as well as the resulting outcome if the drug is not provided to the individual. Other factors considered include the clinical knowledge of the patient, the disease and its history of progression, and any known adverse effects associated with a drug.
Drug elimination is the result of metabolic activity upon the drug and the subsequent excretion of the drug from the body. Metabolic activity can take place within the vascular supply and/or within cellular compartments or organs. The liver is a principal site of drug metabolism. The metabolic process can be broken down into synthetic and nonsynthetic ractions. In nonsynthetic reactions, the drug is chemically altered by oxidation, reduction, hydrolysis, or any combination of the aforementioned processes. These processes are collectively referred to as Phase I reactions.
In Phase II reactions, also known as synthetic reactions or conjugations, the parent drug, or intermediate metabolites thereof, are combined with endogenous substrates to yield an addition or conjugation product. Metabolites formed in synthetic reactions are, typically, more polar and biologically inactive. As a result, these metabolites are more easily excreted via the kidneys (in urine) or the liver (in bile). Synthetic reactions include glucuronidation, amino acid conjugation, acetylation, sulfoconjugation, and methylation.